m = {1: "数加", 2: "java", 3: "python"}

print(m)
print(m[2])  # 通过key获取value

print(m.keys())
print(m.values())

# 增加元素
m[4] = "hadoop"

print(m)

print(m.get(6))

# 判断key是否存在
print(3 in m)

del m[1]
print(m)
print(m.pop(3))
print(m)